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THE INSECTS— ARTHROPODS 



Photos by Cornelia Clarke 



Fig. 15.6. Complete metamorphosis, illustrated by the monarch butterfly. The highly 

 magnified egg is shown at the upper left. This hatches into a worm-like larva that 

 feeds extensively. In the upper right the larva prepares to form the pupa. The 

 quiescent pupa is shown in the lower center and the adult butterfly emerging from 

 the pupa case at the lower right. 



big or little flies when they leave the pupa case and retain their size 

 throughout their lives. This is because of the confining exoskeleton. 

 The second method of insect development is called gradual meta- 

 morphosis. In this method, which may be illustrated by the grass- 

 hopper, the egg hatches into something that resembles the adult, but 

 must undergo a series of gradual changes before it becomes the adult 

 type. The immature stages of such metamorphosis are called nymphs. 

 A newly hatched grasshopper nymph can be recognized as a grasshop- 

 per; it feeds in the same way as the adult and lives in the same type of 

 environment, but its body proportions are somewhat different. It has 

 no wings, its body is proportionately shorter, and the hind legs are not 

 as well adapted to jumping as in the adult. It increases its size and be- 



